MadSpin and MadGraph decay widths
Hi I put my cards in here.
The issue is this :
we are making
process p p > n1 mu [QCD]
with
decay n1 > ptl ptl ptl
(here, ptl are some mixtures of leptons and jets)
For other normal mass points for n1 (15~75 GeV) & (85~2000 GeV) the generations and cross section results are fine.
However, for mn1 = 80 GeV there's a bit problem.
“CRITICAL : Branching ratio larger than one for 9900012"
We get an error message like above and the result is odd.
Branching ratio for that mass point is bigger than 1 which does not make sense physically
(I put the cards in [1] and you will be able to reproduce them)
I guess that it is due to the mn1 = 80 GeV is very similar to mass of W boson 80.4 GeV and this makes the decay weird.
However we still are not sure where this problem is from, yet.
In this kind of situation, is there any suggestions to get a correct cross section for 80gev mass point?
And do you think it's ok to believe the event kinematics which madgraph produces in these kind of cases?
Thanks, Sihyun Jeon.
PS I just checked LO generation by :
(generate p p > n1 l, n1 > l j j)
and compared it with
(generate p p > n1 l)
Above is "exclusive dilepton channel" generation and below is "inclusive n1 production" so we would expect
xsec(p p > n1 l, n1 > l l j j) = xsec(p p > n1 l) * BR(n1 > l j j ).
Howver my result shows that BR(n1 > l j j) > 1.0 which does not make sense for LO as well, so this is not a problem caused by use of MadSpin...
[1] https:/
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